The present invention relates generally to controllers for a combustion system for a gas turbine. In particular, the invention relates to a combustor control algorithm for a Dry Low NOx (DLN) combustor.
Industrial and power generation gas turbines have control systems (“controllers”) that monitor and control their operation. These controllers govern the combustion system of the gas turbine. To minimize emissions of carbon-monoxide and nitric-oxides (NOx), DLN combustion systems may include control scheduling algorithms that receive as inputs measurements of the exhaust temperature of the turbine, the actual operating compressor pressure ratio, and the actual emissions levels.
Emissions sensors are needed to monitor emission levels in the turbine exhaust. Industrial gas turbine engine control systems generally employ triplex redundancy for control process and safety critical sensors. Triplex redundancy is often needed to satisfy safety and reliability expectations and requirements of customers and governmental agencies. Providing three emission sensors for a turbine exhaust is expensive, and adds to the maintenance and calibration requirements of the gas turbine. There is a need for a cost effective approach to directly controlling emission levels in a gas turbine.